Authorities allege the pair operated a handful of area businesses portrayed as massage parlors that were in fact fronts for a human trafficking operation. They included Asian Bodywork a.k.a. Woburn Wellness Bodywork in Woburn, along with five others in Bedford, Billerica, Medford, Reading and Wilmington.

"Through our investigation, we believe the women involved were bused in from multiple locations, including New York. We allege these women were kept in deplorable conditions, often confined to a single room with few mattresses on the floor and they were told to work seven days a week at various location," Coakley said at a press conference at the Wilmington police station.

She was accompanied by local police chiefs and representatives from Homeland Security. The victims are said to have been in the country legally.

Sex trafficking is the second largest criminal enterprise in the world, according to Coakley.

"The trafficking of women and other victims is often out of public view, in fact, that’s how it’s been successful, but it is happening right here in our communities. This case is just the latest example," Coakley said.

Chen was arrested in Reading and Keplin was arrested in Woburn. Each face one count of trafficking of persons for sexual servitude, six counts of deriving support from prostitution and one count of keeping a house of ill fame.

The pair was arraigned Tuesday in Somerville District Court. They each pleaded not guilty to the charges. Judge Neil Walker set bail at $250,000 for each with the conditions that they surrender their passports, remain on home confinement and be monitored by GPS device if released on bail.

"It is estimated 800,000 men, women and children are trafficked around the world each year. These victims are trafficked into commercial sex trade and forced labor situations," Michael Netherland, deputy special agent in charge of Homeland Security Investigations, said Monday.

Victims were allegedly lured with false promises of good-paying jobs and instead coerced into prostitution, domestic servitude, factory and farm work or other types of forced labor. Victim identification is the greatest challenging in fighting human trafficking, according to Netherland.

Many victims come from foreign nations and do not speak English. They were stripped of identification documents and threatened with physical or financial harm if they tried to escape, according to investigators.

Authorities allege that Chen and Keplin drew in women from across the Eastern seaboard and advertised sexual services on websites known to advertise prostitution, set up appointments for sexual encounters for the women and managed the financial components of the organization.

The two also allegedly arranged for overcrowded housing for the women and facilitated the daily transportation of the women to and from the businesses.

The six local business were searched with police warrants on Monday by local and federal law enforcement.

"Today’s arrests were the culmination of a cooperative and comprehensive investigation between state, federal and many local law enforcement agencies coordinated by the Attorney General's office," Woburn Police Chief Robert Ferullo said in a statement Monday. "This operation is a significant step in dealing with the wide spread problem of human trafficking and prostitution is our communities."

The investigation is ongoing. Coakley said there may be additional charges filed.